1. Field of the Invention
The present invention relates to an auxiliary power device capable of mounting on and removing from a wheelchair.
2. Description of the Related. Art
In developed countries, with rapid progress of aging of population and decreasing number of children, introduction of the public nursing-care insurance system, or the like, there has been increasing necessity or expectation for development of welfare related to supportive devices. A wheelchair, which is one of movement supportive devices, is useful for people who have difficulty in walking on account of injuries, diseases, or disabilities. However, when using a hand-operated wheelchair, labor is needed in travelling in a place where there is a slope or level difference in the way. Particularly, when a user (one on the wheelchair) is tired and tries to rest his hands, the wheelchair may start to retreat on an uphill road, while speed of the wheelchair may become excessive against the will of the user on a downhill road. On the other hand, a motorized wheelchair, which is commercialized to solve such problems, is not only expensive but also has a problem that choice of the wheelchair is limited because of a limited number of varieties available, thus selection of the one best fitted for the user cannot always be made.
Accordingly, an auxiliary power device is proposed which is capable of being mounted on and removed from a habituated hand-operated wheelchair and of providing power assistance to the hand-operated wheelchair. For example, Japanese Patent Application Laid-open No.11-178859 discloses an outside fitting type of auxiliary power device, which can be mounted on and removed from by a mechanical toggle mechanism. Specifically, at both right and left ends of the auxiliary power device, open grooves are formed which can be fitted with lower frames of a wheelchair. When the auxiliary power device is mounted on the wheelchair, the lower frames of the wheelchair are fitted into the open grooves, and then handles are operated to tighten clamps. In this way, the auxiliary power device is fixed to the lower frames of the wheelchair. Contrarily, when the auxiliary power device is removed, the handles are operated to release the clamps.
However, in the above-described outside fitting type of auxiliary power device, at each time of mounting and removing thereof, the mechanical machinery needs to be manually operated. Accordingly, when the auxiliary power device is repeatedly mounted and removed, some users may feel that such workings are inconvenient. Also, there is a problem that the mounted auxiliary power device may be off the wheelchair while travelling, when the clamps come loose.
Accordingly, it is an object of the present invention to provide improvement in convenience of an outside fitting type of auxiliary power device by making it automatically and securely mountable and removable to a habituated wheelchair.
In order to solve the above-described problems, a first aspect of the present invention provides an auxiliary power device, which can be voluntarily mounted on and removed from a wheelchair and provides adequate power assistance to the wheelchair, comprising position detecting means for detecting the positions of predetermined frames of the wheelchair, engaging means having handles at outer ends thereof, each of the handles having a shape which can be engaged with the frame, driving means for displacing the engaging means, and control means for displacing the engaging means by the driving means when the frames are determined to be at the predetermined position based on information from the position detecting means to allows the handles to engage with the frames.
Here, it is preferable that the above-described position detecting means detects right and left frames of the wheelchair, and the engaging means has a first arm which can be displaced toward the left frame of the wheelchair and a second arm which can be displaced toward the right frame of the wheelchair. In this case, the control means displaces each of the arms by the driving means when the right and left frames are determined to be at the predetermined positions, and renders the first and second arm with the handles to grasp the right and left frames.
Further, the above-described handles are pivotably attached to the arms. It is preferable that each of the handles further comprises rotational angle detecting means for detecting rotational angle of the handle with respect to the arm, and calculating means for calculating inclination of a travelling road based on the rotational angle of the handle detected by the rotational angle detecting means in a state where the handle is engaged with the frame.
Furthermore, the above-described driving means comprises an electric motor, and load detecting means for detecting a load state of the electric motor. In this case, the control means stops driving of the electric motor when the load of the electric motor becomes larger than the predetermined value after the engaging means starts to be displaced.
Moreover, it is preferable that the above-described control means allows the auxiliary power device to move when the frames are determined to be not at the predetermined position, so that the frames can be positioned at the predetermined positions.
Furthermore, it is preferable that when one of the right and left frames is determined to be at the predetermined position, the control means displaces the arm on a side engaging with the frame, and allows the auxiliary power device to move so that the other of the right and left frames can be positioned at the predetermined position.
On the other hand, a second aspect of the present invention provides an auxiliary power device of a wheelchair which provides power assistance in accordance with inclination of the travelling road comprising arms for grasping frames of the wheelchair, handles pivotably attached to both outer ends of the arms and having a shape capable of engaging with the frame of the wheelchair in order to grasp the frames, detecting means for detecting rotational angles of the handles relative to the arms, and specifying means for specifying an inclination state of a travelling road based on the rotational angles of the handles detected by the detecting means in a state where the frames are grasped by the arms with the frames.
Here, it is preferable that the above-described specifying means detects a position in which the inclination of the travelling road is determined to vary based on variation of the rotational angles of the handles.